General Chemistry Reactant question

Question

I have no idea how to do the following problem...

 

"If you wish to prepare 2.00 g of BaSO4 (233.43 g/mol) from 1.5 M Na2SO4 (142.04 g/mol) and 1.0 M BaCl2 (208.23 g/mol) how many milliliters (mL) of 1.0 M BaCl2 will you need assuming 100% of the BaCl2 reacts and precipitates to give the desires BaSO4?"

Answer 1

First you need to write down the chemical equation for the precipitation reaction of BaSO4 and make sure that it is balanced. The rest of the problem is just a stoichiometry question. To determine the volume of BaCl2 required to react with Na2SO4 to give solid BaSO4 you need to use the information that you're given. In the question you're given the mass of BaSO4 and its molecular weight from which you can find out how many moles of BaSO4 are produced. Then using the balanced chemical equation you need to set up a ratio between BaCl2 and BaSO4 from which you can find how many moles of BaCl2 are required to precipitate BaSO4. Finally using the given concentration of BaCl2 and the formula for calculating molarity: M = mol/volume you can find the required volume of BaCl2.

 

Also note that in this question you do not need to worry about limiting reagents since you're assuming that all of the BaCl2 solution reacts.